~Snip~
Real Madrid are favourites to win the home leg, but they are no longer favourites to progress to the semi-finals if they fail to score a few goals without conceding in the first half. Arsenal will certainly not play defensively in the second leg, if Arteta does so then Arsenal are clearly at great risk of conceding a lot of goals. Arsenal have a high chance of progressing to the semi-finals after they managed to create a 3-0 aggregate in the first leg, that is an advantage that will really help them in the second leg later.
I totally agree with your statement, Real Madrid might win, but they have little chance of making it to the semifinals. Their task this time is very difficult, they must score at least three goals to force Arsenal to continue the match into extra time.
Yes, Arsenal cannot play defensively because Madrid attack is very dangerous. Arteta must not take risks in the second leg, Arsenal must be able to match Madrid game if they do not want to lose their chance to advance to the semifinals.
Real Madrid has turned things around in critical moments and they have proven it so that Real Madrid is considered a team that has a mentality above the average of other teams when they play in the Champion League competition, but this season I think it's a little different, especially in the last few matches it has been proven that Real Madrid's performance has declined, especially their attack line which is less productive in scoring goals, so that makes me pessimistic that Real Madrid can turn things around in the second leg later, in terms of percentage, Real Madrid's chances are now very small.